The long-term objective of this research is to specify the chromosomal location of genes involved in individual variation in taste. Exploiting taste polymorphisms that have already been discovered in inbred strains, we will explore the following modalities with the associated recombinant inbred (RI) sets: sweet (BXD, AXB, BXH, NZXSM) and bitter (BXD, AXB, BXH, NZXSM). After careful concentration/preference studies are carried out in the parental strains on selected gustatory stimuli within each modality-sweet (sucrose, fructose, saccharin, d-phenylalanine, 1-proline) and bitter (quinine, strychnine, sucrose-octaacetate, denatonium)--the RI sets will be screened on specific concentrations of the relevant solutions and strain distribution patterns (SDP's) developed. If the SDP's are consistent with their determination by a major gene, linkage will be assessed by comparing the SDP's to the existing database of genetic markers in Manly's RI-Manager (a computer program). Preliminary linkages so detected will be further tested by breeding F2 generations from relevant progenitors and typing individual animals on gustatory phenotype and molecular markers using the PCR-methodology. In addition to gene-mapping, the following studies will be performed to study intra- and inter-modality relationships: 1. Strain means on the various solutions will be subjected to multivariate correlational and cluster analysis in-and attempt to discover the effect of genes both within and between modalities, and 2. The conditioned taste-aversion technique will be applied to selected strain differences to discover if variations in preference/aversion are based on genetic alterations in detection thresholds. Mapping chromosomal regions containing "taste" relevant genes is an important first step toward obtaining a more precise location for the gene by other methods and this should ultimately lead to the identification and sequencing of the gene. Such knowledge will be invaluable in relating the action of the relevant genes to specific kinds of taste receptors and modality-specific neuronal response.